ma 


2.  , 


ESSENTIAL  FACTS 
ABOUT  PAPER 


By 
WILLIAM  BOND  WHEELWRIGHT 

AUTHOR    OF    FROM    PAPER    MILL 
TO  PRESS  ROOM,  ETC. 


Beg.  U.  3.  Pat.  OS. 


Privately  Printed  for 
STONE  &  ANDREW,  INC.,  BOSTON 


Copyrighted  1920 

By 
WILLIAM  BOKD  WHEELWRIGHT 


Price  One  Dollar 


TABLE  OF  CONTENTS 

CHAPTER 

FOREWORD 5 

I.   PRINCIPAL  RAW  MATERIALS       ...  7 

II.   PAPER  MAKING — THE  BEATER  ROOM    .  12 

III.   PAPER  MAKING — THE  MACHINE  ROOM  16 

IV.   PAPER  MAKING — FINISHING       ...  27 

V.   THE  PHYSICS  OF  PAPER 32 

VI.   QUALITY  AND  TESTING 36 


17107C7 


LIST   OF   ILLUSTRATIONS 

FACING 
PAGE 

RAG  ROOM 10 

RAG  BOILER 14 

BEATER  ROOM 18 

MECHANISM  OF  A  JORDAN  ENGINE      ...  22 

WET  END  OF  FOURDRINIER  MACHINE      .      .  26 

CALENDER  END  OF  FOURDRINIER  MACHINE     .  30 

COATING  PAPER 32 

SUPER  CALENDERS  34 


FOREWORD 

The  United  States  is  the  largest  producer  of 
paper  in  the  world,  making  annually  a  tonnage 
larger  than  that  of  any  other  five  nations  combined. 

Over  seven  hundred  mills  are  engaged  in  the  pro- 
duction of  this  commodity  in  our  country,  and  the 
uses  for  paper  have  become  so  extensive  as  almost 
to  baffle  enumeration,  and  to  require  a  high  degree 
of  specialization  in  its  purchase  and  distribution. 

Long  training  and  efficient  organizations  are 
requisite  to  maintain  familiarity  with  both  the 
sources  and  the  market.  The  large  variety  and 
quantity  of  stock  sufficient  to  satisfy  the  diversity 
demanded  in  the  trade  has  made  the  Paper  merchant 
a  permanent  and  necessary  economic  factor. 

In  the  conduct  of  this  business  we  recognize  intel- 
ligence and  service  as  prime  factors  for  winning  and 
holding  a  satisfied  clientele.  Many  of  the  old  school 
merchants  operated  on  the  basis  that  the  less  their 
customers  knew  about  paper  the  better  it  was  for 
themselves,  as  that  would  make  them  more  depen- 
dent upon  them.  We  feel  that  the  reverse  is  the 
case,  and  that  the  more  helpful  information  we  can 
give,  the  better  we  are  serving.  It  is  with  this 
thought  and  wish  that  we  have  had  this  book  of 
ESSENTIAL  FACTS  ABOUT  PAPER  prepared,  and  pre- 
sent it  to  our  friends  with  the  hope  that  they  may 
find  its  contents  useful. 


CHAPTER  I 


PRINCIPAL   RAW   MATERIALS 

Fibres  which  comprise  the  chief  raw  material  in 
paper  making  are  invariably  some  form  of  cellulose. 
These  cellulose  fibres  differ  in  purity,  form,  and 
length  as  they  exist  in  the  raw  state.  Consequently 
the  paper  maker  selects  them  in  reference  to  the  use 
for  which  the  paper  he  makes  is  intended.  The 
purest  form  in  which  cellulose  fibres  naturally  occur 
as  raw  material  available  for  paper  making  is  in 
cotton  and  linen  cuttings  and  rags.  Such  fibres  are 
practically  pure  cellulose,  their  impurities  consisting 
mainly  of  sizing  and  dyes. 

Cotton  Fibre 

Cotton  fibre  is  long  and  tubular  and  when  dry 
collapses  and  twists  spirally,  thus  in  the  mass  of 
paper  effecting  especially  good  adhesions,  one  with 
the  other.  Papers  made  exclusively  from  cotton 
fibre  are  strong  and  flexible  excepting,  of  course, 
specialty  papers  such  as  blotting. 

Ldnen  Fibre 

Linen  fibre  like  cotton  is  tubular,  but  has  thicker 
walls  which  are  jointed  like  a  cane  or  rush.  They 
are  long,  strong,  and  flexible  and  form  compactly, 
making  a  strong,  hard  paper  of  great  durability.  A 
noted  English  Authority,  Mr.  J.  W.  Wyatt,  says, 
"With  long  and  careful  manipulation  in  the  pulp- 
ing engines,  taking  precautions  to  draw  the  fibre  and 


8  ESSENTIAJL  FACTS  ABOUT  PAPER 

not  to  cut  it,  new  cotton  will  give  a  stronger  and 
much  closer  paper  than  new  linen.  The  linen  fibre, 
under  the  beating-rolls  absorbs  water  more  readily 
than  the  cotton  fibre,  and  works  up  into  a  more 
'greasy'  and  wet  state  necessary  for  a  stiff,  firm 
sheet  of  finished  paper,  but  it  does  not  with  that 
necessarily  develop  strength. 

"After  numerous  trials  to  obtain  a  strong 
machine-made  paper,  the  strongest  was  produced 
with  new  cotton  intimately  mixed  with  about  one- 
fifth  or  one-sixth  of  its  bulk  of  new  linen." 

The  quality  of  rag  paper  varies  according  to  the 
newness  and  condition  of  the  rags  or  cuttings  used 
in  their  making  as  well  as  in  the  manipulation  of  the 
stock.  Hence,  the  percentage  of  rag  in  paper  is  not 
a  positive  criterion  of  the  quality.  Color  and 
strength  must  also  be  considered. 

Hemp 

Hemp  derived  from  ropes,  course  bags,  etc.,  yields 
a  very  strong  fibre,  Manila  hemp  giving  the  best 
quality. 

Jute 

Jute,  which  is  the  fibre  of  an  Indian  plant,  also 
yields  a  very  strong  fibre,  but  neither  of  the  latter 
two  fibres  are  easy  to  bleach  and  would  consequently 
not  be  used  for  white  paper. 

Esparto  Fibre 

Esparto  fibre  is  extensively  used  in  England  and 
is  derived  from  a  grass  grown  in  Northern  Africa. 


ESSENTIAL  FACTS  ABOUT  PAPER  9 

It  is  not  available  for  American  manufacture,  but 
produces  a  raw  material  on  a  par  with  the  best 
bleached  sulphite  pulps. 

Ground  Wood  Pulp 

The  lowest  grade  of  wood  pulp  consists  in  the 
ground  up  fibres  of  spruce  logs  from  which  the 
bark  has,  of  course,  been  removed.  Containing  as  it 
does  considerable  non-cellulose  material,  it  is  not 
suitable  for  papers  of  permanent  value,  both  because 
it  grows  brittle,  and  becomes  discolored  through 
the  action  of  light  and  air. 

Chemical  Wood  Pulps 

Chemical  wood  pulp  is  virtually  pure  cellulose 
fibre  obtained  by  the  chemical  treatment  of  wood 
chips,  whereby  the  non-cellulose  constituents  are 
eliminated.  The  yield  of  cellulose  from  wood  is 
almost  53%. 

The  strength  and  quality  vary  with  the  wood  used 
and  the  process  employed.  A  soft  pulp  is  obtained 
by  the  "Soda"  process  from  aspen  and  poplar  wood 
and  is  known  as  "Soda  Pulp."  A  strong  pulp  is 
obtained  from  spruce  or  other  coniferous  wood  by 
digestion  in  sulphite  or  sulphate  liquor.  Sulphite 
pulp  for  white  papers  must  naturally  be  bleached, 
though  in  cheaper  grades  the  unbleached  sulphite 
may  be  used  in  combination  with  whiter  fibres  de- 
rived from  old  papers  worked  over  and  "Soda 
Pulp."  Sulphate  pulp  is  particularly  strong  and  is 
used  exclusively  in  wrapping  papers. 


10  ESSENTIAL  FACTS  ABOUT  PAPER 

Waste  Paper 

Waste  Papers  form  an  important  source  of  paper 
making  material.  In  cheap  grades  where  color  is 
of  no  importance  they  are  used  just  as  they  come  in 
the  bale.  The  better  grades  of  waste  must  neces- 
sarily be  sorted.  White  Shavings  come  first  in  value 
as  they  are  suitable  for  repulping  after  having  been 
dusted.  Books  and  magazines  must  be  sorted, 
dusted,  and  cooked  with  alkali  to  render  the  ink 
soluble.  Then  follows  a  process  of  breaking,  wash- 
ing, and  bleaching  to  make  a  pulp  suitable  for  white 
paper.  Newspaper  and  other  stock  containing 
much  ground  wood  cannot  be  successfully  de-inked, 
and  is  hence  valueless  for  making  into  white  paper. 

The  proportionate  use  of  the  various  fibres  in  the 
United  States  is  approximately  as  follows : 

Wood  Pulp 61.6% 

in  the  following  proportions: 

Ground  Wood,  47%;    Sulphite,  4-2%; 

Soda,  11%. 

Waste  Papers 21.4% 

Rags 7.8 

Straw 6.6 

Manila  (Rope) 2.6 

With  the  steady  diminution  of  the  pulp  wood 
supply  in  the  United  States,  the  saving  of  Waste 
Papers  is  becoming  increasingly  more  profitable  and 
important. 

Filler 

Many  kinds  of  paper  contain  some  form  of  min- 
eral filler.  Especially  is  it  necessary  in  order  to 
make  smooth  surfaced  paper  or  to  increase  the 


ESSENTIAL  FACTS  ABOUT  PAPER  11 

opacity.    It  is  used  principally  in  book  papers  and 
bristol  boards,  and  coated  papers. 

China  Clay  is  the  best  grade  because  it  is  powdery 
and  soft.  A  cheaper  substitute,  Talc,  is  crystalline 
in  structure  and  papers  containing  considerable  per- 
centages are  much  harder  on  the  cutter  knives  and 
more  wearing  on  printing  plates.  Clay  is  the  prin- 
cipal component  of  coating  mixtures  in  combination 
with  casein  as  an  adhesive. 

Sizing 

Rosin  size  is  prepared  by  cooking  rosin  with  alkali 
to  form  a  soap  which  when  added  to  the  stock  in  the 
beating  engines,  renders  it  less  absorbent.  Starch 
and  Silicate  of  Soda  are  similarly  used. 

Animal  size  is  prepared  by  cooking  clippings  of 
hides,  hoofs,  etc.,  and  is  applied  to  the  surface  of 
the  paper  which  passes  through  a  size  vat  during  its 
manufacture.  Its  use  is  confined  to  papers  intended 
for  writing. 

Color 

The  vast  majority  of  dyes  now  used  in  the  Paper 
industry  are  anilines.  Some  of  them  are  non-fading 
and  others  are  not — exposure  to  sunlight  will  quick- 
ly determine  which  is  the  case.  Some  colors,  like 
buff,  are  produced  with  a  mineral.  The  mineral 
colors  are  apt  to  give  a  slightly  lighter  shade  on  the 
under  side  of  the  sheet  as  the  action  of  the  suction 
boxes  on  the  machines  subtracts  a  portion  of  the 
mineral. 


CHAPTER  II 

PAPER  MAKING THE  BEATER  ROOM 

It  should  always  be  borne  in  mind  that  the  pro- 
cesses of  Paper  making  are  difficult  to  carry  on  with 
precision  because  so  much  must  be  left  to  the  judg- 
ment of  the  men  directing  its  successive  steps.  The 
sorting  of  the  stock,  the  manipulation  in  the  cook- 
ing— the  beating,  and  on  the  paper  machines  is 
susceptible  of  producing  great  variation,  both  inten- 
tional and  unintentional,  in  the  finished  product. 

In  other  words,  the  human  element  enters  most 
decidedly  into  the  manufacture  of  paper.  This  is 
recognized  in  the  prevalent  trades  customs,  which 
specifically  provide  for  a  reasonable  variation  in 
actual  weight  from  the  weight  specified  by  the  cus- 
tomer. But  as  experienced  "paper  men"  know,  the 
variation  is  not  confined  to  weight  alone,  and 
involves  also  formation,  color,  and  finish.  Strict 
attention  to  business  is  the  prerequisite  for  uniform 
paper  making.  Scientific  management  and  constant 
painstaking  work  all  along  the  line  determine  who 
is  the  dependable  paper  maker,  and  hence  what 
brands  may  gain  pre-eminence,  in  the  confidence  of 
buyers  and  the  satisfaction  of  customers. 

FIVE  MAIN  STEPS  IN  MANUFACTURE 

1.  Separation    of    paper    making    fibre    (cellulose) 

from  its  natural  state. 

2.  Conversion  of  cellulose  into  "half  stuff"  or  pulp. 

3.  The  Beating  of  the  fibres  and  their  blending  with 

other  necessary  constituents  into  paper  making 
"stuff." 

4.  The  manufacture  of  stuff  into  Paper. 

5.  Processes  of  finishing. 

12 


ESSENTIAL  FACTS  ABOUT  PAPER  13 

It  is  not  essential  here,  to  dwell  upon  the  first  two 
steps.  The  third  step  is  the  most  potent  of  all  in 
determining  results. 

The  physical  action  of  the  so-called  beating  of  the 
fibres  is  capable  of  producing  divergent  results,  as 
it  causes  subtle  chemical  changes  as  well  as  physical 
changes  in  the  fibre.  For  example,  by  beating  the 
fibres  quickly  with  sharp  "tackle"  the  maximum 
absorbency  is  obtained,  as  is  desired  in  blotting 
papers,  whereas  a  prolonged  beating  with  dull 
"tackle"  attenuates  the  fibres,  leaving  them  with 
frazzled  ends  which  helps  to  give  strength,  and  also 
"hydrates"  the  cellulose  so  that  it  works  up  into  a 
harder,  denser  sheet. 

The  Beating  engine  consists  of  a  large,  oblong 
tub  divided  into  halves  by  a  partition  which  stops 
short  of  the  ends,  thus  leaving  a  channel.  On  one 
side  of  this  partition,  located  about  two-thirds  of 
the  way  from  one  end,  is  a  large  roll  just  the  width 
of  the  channel.  This  is  shod  with  iron  bars  running 
parallel  to  its  axis  and  protruding  about  an  inch 
from  the  surface  all  around  the  roll.  A  so-called 
bed  plate  similarly  imbedded  with  bars  extends 
across  the  tub  just  under  the  axis  of  the  roll.  By 
mechanical  means  the  roll  may  be  raised  off  the  bed 
plate  as  the  judgment  of  the  "beater  engineer"  dic- 
tates in  order  to  regulate  the  length  of  fibre,  as  the 
stock  circulates  in  the  tub  and  passes  between  the 
roll  and  bed  plate. 

It  is  usual  to  begin  by  partially  filling  the  tub 
with  water,  then  adding  a  suitable  quantity  of  pulp. 
When  this  is  partially  broken  up,  other  ingredients 


14  ESSENTIAL  FACTS  ABOUT  PAPER 

required,  such  as  color,  size,  and  filler,  are  intro- 
duced and  the  circulation  of  the  mixture  is  main- 
tained for  the  proper  length  of  time.  [Whereupon 
a  valve  in  the  floor  of  the  tub  is  opened  and  the  stock 
pours  into  one  of  a  pair  of  reservoirs  or  "chests," 
from  which  it  is  pumped  up  to  be  passed  through 
a  "Jordan"  engine  which  refines  the  pulp  and  regu- 
lates the  length  of  fibre  on  its  way  to  the  machine 
chest.  While  one  "Jordan  Chest"  is  being  emptied, 
the  other  is  filled,  hence  a  constant  supply  of  stuff 
is  maintained  in  the  right  condition  for  paper 
making. 

It  should  be  explained  that  the  mill  superinten- 
dent supplies  the  beater  man  with  a  formula  called 
the  "furnish"  for  each  run  of  paper.  This  indicates 
the  exact  amount  of  each  kind  of  pulp,  the  quantity 
of  filler,  size,  color  or  whatever  ingredients  are  re- 
quired for  the  order.  The  manipulation  of  the  stock 
is  handled  by  the  beater  man  in  accordance  with  the 
practise  of  the  mill. 

Again  it  should  be  noted  that  the  beating  lasts 
any  where  from  an  hour  to  several  hours  according 
to  the  kind  of  paper  being  made,  and  the  judg- 
ment on  the  part  of  the  man  in  charge.  It  is  an 
"old  saw"  in  the  trade  that  "the  paper  is  made  in  the 
beaters,"  which  means  to  say  that  the  character  of 
the  finished  sheet  is  very  greatly  influenced  by  the 
manipulation  of  the  stock  at  this  stage.  Naturally, 
the  length  of  the  fibres  cannot  be  altered  after  the 
beating  process  is  completed,  nor  can  any  of  its  in- 
gredients, except  color,  be  modified.  The  consis- 
tency, however,  is  alterable  by  the  control  of  water 


ESSENTIAL  FACTS  ABOUT  PAPER  15 

on  the  paper  machine  itself,  and  this  introduces 
another  variable  factor  for  which  the  machine  tender 
is  responsible. 


CHAPTER  III 

PAPER  MAKING THE  MACHINE  ROOM 

In  order  to  understand  the  physical  structure  and 
characteristics  of  paper,  it  is  necessary  to  see  how 
the  thousands  of  little  fibres  comprising  it  are  united 
to  form  a  homogeneous  sheet,  and  a  clear  under- 
standing of  paper  structure  may  be  of  great  advan- 
tage to  the  printer. 

First  let  us  see  what  a  paper  machine  is  like  and 
then  it  will  be  easy  to  grasp  the  essential  facts  about 
the  making  of  a  sheet  of  paper. 

Paper  machines  all  have  what  is  known  as  the 
"wet  end,"  and  the  "dry  end."  The  function  of  the 
wet  end  is  to  receive  the  volume  of  water  in  which 
the  fibres  and  other  components  are  suspended  as  it 
comes  from  the  beater  room,  and  form  them  into  a 
moist  web.  The  function  of  the  diy  end  is  to  expel 
the  moisture  and  impart  the  desired  finish. 

The  Fourdrinier  Machine 

There  are  two  principal  kinds  of  wet  ends,  the 
Fourdrinier  and  the  Cylinder.  The  Fourdrinier 
part  consists  of  a  long  frame  across  which  lie  a  level 
series  of  closely  spaced  "table"  rolls  about  four 
inches  in  diameter.  At  either  end  is  a  much  larger 
roll,  the  first  of  which  is  called  a  "breast"  roll,  and 
the  last  a  "couch"  roll.  In  the  lower  part  of  the 
frame  are  a  number  of  rolls  called  "guide"  rolls 
and  "stretch"  rolls.  An  endless  woven  wire  cloth, 
technically  called  "the  wire,"  is  stretched  over  these 
rolls  and  kept  taut  by  the  lower  rolls  which  are  ad- 

16 


ESSENTIAL  FACTS  ABOUT  PAPER  17 

justable.  Near  the  couch  roll  a  couple  of  suction 
boxes  are  introduced  between  the  table  rolls,  and  on 
a  level  with  them,  so  that  the  wire  cloth  passes  in 
close  contact  with  them.  Immediately  under  the 
wire  is  a  long  pan  or  "save-all"  to  catch  the  drip- 
pings, which  are  pumped  back  to  the  "flow  box." 
The  couch  roll  may  be  of  the  suction  type,  which 
exhausts  the  water  from  the  web  of  paper  by  a 
vacuum  process,  or  it  may  be  of  the  double  type, 
i.  e.,  a  pair  of  rolls,  the  bottom  one  about  which  the 
wire  turns,  and  the  top  jacketed  with  felt  to  squeeze 
the  water  out  of  the  paper  web  on  its  passage  be- 
tween the  rolls.  In  order  to  control  the  width  of  this 
web  and  prevent  the  stuff  from  running  off  the 
sides  of  the  machine,  there  are  endless  rubber  straps 
on  each  side  of  the  machine  called  "deckles."  They 
run  over  pulleys  attached  to  the  frame  in  such  a 
position  that  the  bottom  part  of  the  strap  rests  upon 
the  wire  and  travels  with  it.  These  straps  may  be 
set  at  any  distance  from  one  another  according  to 
the  dimensions  required  by  the  paper  order.  Just 
back  of  the  deckle  straps  extending  across  the  wire 
are  two  adjustable  "slices"  which  hold  back  the 
paper  making  stuff  so  that  a  so-called  "pond"  is 
formed  where  it  first  flows  onto  the  machine.  There 
is  a  joint  in  the  first  part  of  the  frame  to  permit  of 
a  lateral  shaking  of  the  frame,  which  assists  in  inter- 
weaving the  fibres  and  counteracts  the  natural  ten- 
dency for  them  all  to  point  in  the  direction  of  the 
flow  of  the  stuff  along  the  machine. 

When  the  paper  maker  is  ready,  he  throws  in  a 
lever  starting  the  couch  roll  which  supplies  the  trans- 


18  ESSENTIAL  FACTS  ABOUT  PAPER 

mission  power  for  the  "wire."  Next  he  opens  the 
valves  of  the  flow  box  that  supplies  the  paper 
making  stuff,  which  wells  over  the  breast  roll  cover- 
ing the  entire  width  of  the  machine,  and  a  rapidly 
forming  felt  of  paper  is  carried  forward  on  the  wire. 
As  remarked  above,  the  slices  hold  back  the  stuff  in 
a  "pond,"  and  the  lateral  shake  of  the  frame  under- 
neath this  pond  weaves  the  fibres  as  the  passage  of 
the  water  through  the  wire  cloth  into  the  "save-all" 
is  depositing  them  upon  the  wire. 

All  the  way  along  the  course  of  the  wire  to  the 
couch  roll,  the  water  may  be  seen  draining  from  the 
moist  web  into  the  save-all.  The  suction  boxes  are 
used  to  assist  in  getting  rid  of  the  water,  for  after 
the  fibres  are  set  by  this  filtration  of  water  through 
the  wire  cloth,  the  problem  of  the  paper  maker  is  to 
get  rid  of  the  excess  moisture  by  draining,  suction, 
pressure,  and  finally  evaporation. 

The  action  of  the  couch  roll  gives  the  web  a  suffi- 
cient adhesion  to  allow  it  to  be  passed  over  the  small 
intervening  space  to  the  first  set  of  press  rolls, 
through  which  it  passes  on  an  endless  felt,  and  so 
on  to  a  second,  and  sometimes  a  third  set  of  press 
rolls,  which  squeeze  out  as  much  water  as  is  possible 
without  injuring  the  texture  of  the  paper.  Then  it 
is  in  condition  to  be  dried. 

Let  us  pause  here  for  a  more  detailed  considera- 
tion of  what  has  been  happening  on  the  wet  end. 
In  the  first  place,  let  me  remark  that  a  cellulose  fibre 
has  a  tremendous  thirst,  and  will  absorb  water  until 
it  is  distended  and  limp.  The  expulsion  of  its  water 
content  has  the  opposite  effect,  the  fibre  shrinking 


ESSENTIAL  FACTS  ABOUT  PAPEE  19 

its  diameter,  twisting  and  becoming  strong  again. 
This  is  the  reason  for  the  steadily  increasing  cohe- 
sion of  the  web  as  it  passes  along  the  machine, 
gradually  acquiring  the  dryness  natural  to  paper. 

We  have  so  far  omitted  mentioning  the  dandy 
roll.  This  is  a  skeleton  cylinder  some  ten  inches  in 
diameter,  and  may  be  covered  with  a  plain  woven 
wire  cloth  or  with  a  special  weave  like  the  seat  of 
the  ancient  paper  makers'  molds,  to  impress  the 
mark  known  as  "laid"  into  the  paper.  The  dandy 
roll  is  located  on  brackets  between  the  suction  boxes 
and  the  couch  roll,  and  as  it  rests  upon  the  wire  it  is 
automatically  rotated  when  the  machine  is  running, 
and  makes  an  impression  upon  the  moist  paper.  If 
water  marks  are  desired  they  are  produced  by  solder- 
ing a  wire  design  upon  the  surface  of  the  dandy  roll. 
Hence  a  depression  corresponding  to  the  design  is 
indented  in  the  paper  and  the  consequent  thinning 
makes  the  paper  more  translucent,  thus  giving  visi- 
bility to  the  mark. 

The  faster  a  machine  is  run  the  less  is  it  possible 
for  the  shake  to  effect  a  cross  weaving  of  the  fibres. 
The  tensile  strength  of  the  sheet  is  greater  with  the 
grain,  and  consequently  there  is  a  greater  difference 
between  the  tensile  strength  with  the  grain  and 
across  the  grain  of  a  fast  made  paper  than  with  a 
slow  made  paper.  Whether  the  physical  difference 
between  these  papers  is  sufficient  to  compensate  the 
printer  for  the  greater  cost  of  a  slower  production 
depends  upon  the  precise  exactions  of  the  work  in 
hand.  Naturally,  the  grain  of  any  machine-made 
paper  is  quite  marked,  and  has  an  important  bearing 


20  ESSENTIAL  FACTS  ABOUT  PAPEE 

on  the  working  and  binding  of  paper,  which  will  be 
discussed  in  another  chapter  on  the  physics  of  paper, 
but  it  is  appropriate  to  note  at  this  juncture  that  the 
grain  is  more  marked  the  faster  the  paper  is  made, 
as  a  comparison  between  news  print  paper  and  a 
good  book  paper  will  demonstrate. 

The  Cylinder  Machine 

The  Cylinder  wet  end,  while  operating  on  the 
same  principle  as  the  Fourdrinier,  namely  the  de- 
posit of  fibre  by  filtration,  is  entirely  different  me- 
chanically and  produces  a  different  sheet  physically. 

It  consists  of  an  oblong  trough  or  mold  containing 
a  large  skeleton  cylinder  some  three  feet  in  diameter 
which  is  covered  with  a  woven  wire  cloth.  The  mold 
has  two  compartments,  a  rectangular  narrow  one 
into  which  the  "stuff"  is  introduced,  and  a  large  one 
with  a  concave  bottom  closely  conforming  to  the 
periphery  of  the  cylinder.  There  is  a  packing  at 
either  end  so  that  the  water  from  the  smaller  com- 
partment must  pass  through  the  wire  covered  mold 
inside  to  escape  through  a  sluice  at  one  end  of  the 
mold.  A  long  endless  felt  runs  tangent  to  the  top 
of  the  cylinder  and  is  kept  in  contact  by  the  pressure 
of  a  couch  roll.  The  felt  passes  between  squeeze 
rolls,  and  couch  rolls,  and  over  a  suitable  series  of 
guide  rolls.  Its  transmission  comes  from  the  couch 
roll.  The  paper  forms  on  the  outside  of  the  cylinder 
owing  to  the  filtration  of  water  from  the  smaller  to 
the  larger  compartment,  and  as  the  web  encounters 
the  endless  felt,  it  is  picked  cleanly  off  of  the  cylin- 
der, and  carried  along  to  be  pressed. 


ESSENTIAL  FACTS  ABOUT  PAPER  21 

Single  Cylinder  machines  are  used  for  making 
tissue  and  light  wrapping  paper.  Heavier  stocks, 
such  as  cover  or  bristol  board,  are  made  by  a  series 
of  cylinders  rigged  tandem,  some  machines  for  pro- 
ducing the  heavier  boards  having  as  many  as  six  in 
series.  Blanks  are  made  on  such  machines  as  the 
dark,  cheap  middle  can  be  made  from  the  interme- 
diate vats.  Duplex  papers  can  be  made  by  varying 
the  color  of  the  stock  in  the  outer  vats.  There  being 
no  shaking  arrangement  for  such  a  machine,  the 
fibres  lie  largely  in  the  direction  of  rotation  of  the 
cylinder.  Consequently  the  grain  of  a  cylinder 
made  paper  is  very  noticeable. 

We  have  purposely  described  the  two  main  types 
of  wet  ends  before  passing  to  a  description  of  the 
drying  and  calendering,  because  the  dry  ends  of 
both  types  of  machine  are  the  same  with  the  excep- 
tion of  the  "Yankee"  machine,  which  will  be  de- 
scribed later. 

The  paper  maker  naturally  strives  to  expel  as 
much  water  as  possible  by  drainage  and  pressure, 
as  the  evaporation  of  the  remaining  moisture  is  a 
direct  tax  on  his  coal  pile.  The  drying  apparatus 
consists  of  a  series  of  steam-heated  cylinders  36  or 
48  inches  in  diameter,  and  the  web  of  paper  is  passed 
over  the  series  being  held  in  contact  with  the  dryers 
by  a  duck  "dryer  felt."  The  number  and  size  of  the 
dryers  varies  in  accordance  with  the  kind  of  paper 
for  which  the  machine  was  built.  Size  tubs  are  in- 
troduced at  the  end  of  writing  paper  machines  as 
will  be  described  later.  After  the  dryers,  is  placed 
one  or  two  stacks  of  calenders,  which  consist  of  a 


22  ESSENTIAL  FACTS  ABOUT  PAPER 

number  of  chilled  iron  rolls  between  which  the  paper 
is  passed  if  a  smooth  finish  is  required.  According 
to  the  amount  of  finish  required,  the  paper  is 
passed  through  one  or  more  "nips"  of  the  calenders. 
Emerging,  it  is  wound  up  on  a  reel.  There  are 
usually  two  reels  to  a  machine  and  sometimes  three, 
so  that  as  one  is  being  filled  the  paper  from  the  other 
is  being  passed  through  slitters  set  to  divide  the  web 
into  desired  widths  and  is  wound  into  rolls.  In  some 
instances,  of  course,  the  paper  is  given  the  precise 
finish  desired  on  the  machine  itself,  and  is  shipped 
in  rolls.  In  others,  a  special  finish  is  required, 
necessitating  operations  to  be  described  later,  or 
perhaps  it  only  remains  to  cut  the  rolls  transversely 
into  sheets. 

The  Yankee  Machine 

The  "Yankee"  machine  mentioned  previously 
consists  of  a  "Fourdrinier"  wet  end  and  a  single 
dryer  of  large  diameter.  It  is  particularly  con- 
structed for  making  so-called  "machine  glazed"  tis- 
sues, and  specialty  wrapping  papers.  The  peculiar 
effect  of  this  machine  is  to  produce  a  paper  which 
is  glazed  only  on  the  side  that  comes  in  contact  with 
the  face  of  the  dryer. 

Before  passing  to  the  chapter  on  Finishing,  let 
us  review  the  technique  of  paper  making  on  the 
machine,  sufficiently  to  explain  the  principal  effects 
and  defects  which  result. 

The  formation  of  a  sheet  of  paper  is  to  be  judged 
by  looking  through  it.  When  its  appearance  is  even 
and  of  equal  translucence  all  over,  it  is  said  to  be 
"well  formed."  If  the  "look  through"  is  blotchy 


ESSENTIAL  FACTS  ABOUT  PAPER  23 

or  cloudy,  the  paper  is  said  to  be  "wild."  In  other 
words,  the  fibres  are  not  uniformly  deposited  in  the 
making,  and  consequently  the  sheet  is  not  "level," 
but  is  characterized  by  areas  of  varying  thickness. 

In  a  wrapping  paper  or  a  paper  for  ordinary 
printing,  this  is  of  little  importance,  but  for  "offset" 
work  or  for  printing  requiring  an  even  impression 
from  plates,  it  is  obvious  that  a  level,  well-formed 
sheet  is  necessary.  This  quality  is  determined  both 
by  the  stock  and  by  the  skill  with  which  a  machine 
tender  handles  his  "wet  end,"  and  the  proper  beat- 
ing of  the  stock.  The  position  and  distribution  of 
the  fibres  naturally  being  determined  while  the 
water  is  draining  through  the  wire,  no  amount  of 
calendering  can  alter  the  position  in  which  the  fibres 
are  deposited  by  the  water. 

The  grain  of  the  paper,  meaning  the  direction  in 
which  the  fibres  mostly  point,  is  also  determined  at 
the  same  juncture,  and  while  a  majority  will 
naturally  lie  in  the  direction  the  paper  runs  over  the 
machine,  a  skillful  adjustment  of  the  shake,  and 
the  maintenance  of  a  reasonable  speed  improves  the 
weaving,  and  counteracts  this  natural  tendency  to 
point  with  the  stream.  The  impression  of  the  wire 
cloth  is  naturally  imparted  to  a  more  or  less  degree 
upon  the  under  side  of  the  paper,  and  where  refine- 
ment in  this  respect  is  desired  the  paper  maker  must 
use  a  closely  woven  wire  of  fine  strands.  This  adds 
a  bit  to  the  cost  as  a  fine  wire  will  not  last  as  long 
as  a  coarse,  and  more  time  is  lost  in  changing  wires. 

The  difference  between  a  wove  and  a  laid  paper 
is  determined  by  the  kind  of  dandy  roll  used.  The 


24  ESSENTIAL  FACTS  ABOUT  PAPER 

"laid"  is  practically  a  paper  water  marked  with  fine 
parallel  lines,  intercepted  at  short  intervals  by 
coarser  lines  running  at  right  angles.  These  coarser 
lines  always  run  with  the  grain. 

A  cylinder  made  paper  is  always  "wove,"  and 
never  watermarked.  No  light  weight  printing  pa- 
pers are  made  on  such  machines.  There  is,  however, 
a  tendency  in  the  heavier  printing  papers  to  show 
a  "wire"  side,  though  this  can  be  eliminated  by  cer- 
tain arrangements  of  the  molds.  All  cylinder  pa- 
pers split  noticeably  with  the  grain,  and  fold  badly 
across  the  grain  unless  scored. 

The  pressing  of  paper  is  an  important  link  in  its 
making  for  unless  the  rolls  are  maintained  in  proper 
condition  the  water  may  not  be  uniformly  expelled, 
in  which  case  a  damp  streak  will  ensue  and  such 
portions  of  the  web  will  take  a  brighter  finish  in  the 
calenders  than  the  adjacent  areas,  thus  resulting  in 
a  blackened  section.  Such  parts  of  the  web  as  re- 
ceive a  greater  pressure  would  become  thinner.  This 
is  the  cause  frequently  for  soft  ends  in  roll  papers. 

The  weave  and  cleanliness  of  the  felt  used  for 
conveying  the  paper  through  the  presses  is  also  of 
prime  importance  as  the  weave  impresses  itself  into 
the  surface  of  the  paper.  During  the  process  of 
manufacture,  felts  become  filled  in  spots  from  ma- 
terial squeezed  out  of  the  paper,  and  after  that  the 
water  will  not  pass  through  so  quickly.  Hence, 
moist  spots  may  be  left,  and  in  calendering  show  up 
blackened  in  the  finished  paper,  or  as  a  cockled  sur- 
face in  lightly  calendered  paper. 


ESSENTIAL  FACTS  ABOUT  PAPER  25 

Drying 

Coming  to  the  drying  stage,  uniformity  of  con- 
ditions all  the  way  across  the  machine  are  again 
requisite  to  produce  uniformity  of  product.  Fur- 
thermore, it  is  important  not  to  over-dry  the  paper, 
both  because  it  makes  for  brittleness  and  because  it 
produces  an  unstable  condition  in  the  paper,  which 
naturally  contains  a  small  percentage  of  moisture 
varying  with  atmospheric  conditions.  Paper  which 
has  been  dried  much  below  its  normal  moistness 
immediately  seeks  to  absorb  its  natural  moisture 
content  from  the  air,  and  wavy  edges  result.  Over- 
dried  paper  is  also  more  prone  to  becoming  trouble- 
some from  static  or  frictional  electricity. 

Calendering 

The  process  of  calendering  is  to  modify  the 
natural  "egg  shell"  finish  of  paper  as  it  comes  from 
the  dryers,  which  natural  finish  has  been  obtained 
from  the  felts  in  the  presses.  The  usual  finishes  of 
book  papers  are  the  Antique  Wove  and  Laid,  and 
the  Machine  finish.  A  medium  finish  often  known 
as  "Text"  is  produced  with  lighter  calendering 
than  "M.  F.,"  which  requires  rolling  by  the  whole 
stack  of  calenders  instead  of  a  few  "nips."  English 
finish  is  a  smooth,  velvety  machine  finish,  and  re- 
quires a  paper  of  very  close  formation  and  contain- 
ing 15  to  20  percent  of  mineral  filler. 

Surface  Sizing 

Reference  was  earlier  made  to  sizing  apparatus 
for  writing  paper  machines.  The  higher  grade 
writing  bond  and  ledger  papers  besides  being  sized 


26  ESSENTIAL  FACTS  ABOUT  PAPER 

in  the  beaters,  are  surface  sized  by  passing  the  web 
through  a  vat  of  warm  size,  and  then  between  rolls 
which  squeeze  out  the  excess  size.  The  webs  which 
have  been  slit  by  rotary  slitters  located  before  the 
size  vats,  are  now  cut  off  by  a  sheet  cutter  and  piled 
up  on  a  "lay-boy."  Afterwards  they  are  removed 
to  a  drying  loft  and  hung  over  poles  in  quires  to 
dry.  Not  a  few  machines  have  an  arrangement  of 
skeleton  dryers  immediately  after  the  size  vat,  and 
instead  of  slitting  and  cutting  the  web  for  loft  dry- 
ing the  paper,  it  is  dried  by  passage  over  the  air 
dryers  and  slit  like  book  paper,  at  the  end  of  the 
machine,  preparatory  to  subsequent  finishing  pro- 
cesses. Loft  drying  is  traditionally  considered  to 
be  preferable  to  the  air  drying  method  described, 
but  it  is  difficult  to  see  any  reason  why  this  should 
be  true,  and  personally,  I  fail  to  see  the  advantage 
of  this  old  and  more  costly  method. 


CHAPTER  IV 

PAPER  MAKING FINISHING 

Finishing  processes  are  many  and  various  accord- 
ing to  the  class  of  paper. 

Book  Paper 

Book  Papers  with  the  exception  of  Super- 
calendered,  receive  the  desired  surface  on  the  paper 
machine,  and  it  only  remains  to  cut  and  sort  the 
sheets  or  to  pack  in  rolls.  Sheet  cutters  are  built 
so  as  to  cut  a  number  of  sheets  simultaneously  from 
different  rolls.  In  the  case  of  cheaper  papers,  such 
as  the  ordinary  M.  F.  and  S.  &  S.  C.,  as  many  as 
six  or  eight  rolls  may  be  sheeted  together.  The 
disadvantage  of  this  is  that  any  variation  in  weight 
which  may  easily  occur  in  the  making,  results  in  a 
corresponding  inequality  throughout  the  ream  com- 
posed from  so  many  different  rolls.  This  may  be 
reflected  in  an  unevenness  of  presswork.  The  better 
grades  of  book  paper  are  cut  only  one  or  two  rolls 
at  a  time,  which  insures  a  more  uniform  result  as 
well  as  more  careful  sorting,  for  uncoated  book 
paper  gets  no  closer  inspection  than  the  oversight 
of  the  individual  in  charge  of  the  cutter,  whose  duty 
it  is  to  pick  out  imperfect  or  faulty  sheets.  Coated 
paper,  being  prone  to  more  surface  imperfections, 
is  sorted  sheet  by  sheet. 

Super  Calenders 

Super-calendering  gives  the  highest  finish  obtain- 
able to  uncoated  stock,  and  is  a  process  separate 
from  the  machine.  The  paper  is  taken  in  rolls  from 


28  ESSENTIAL  FACTS  ABOUT  PAPER 

the  machine  and  run  in  a  web  through  the  stack. 
The  calenders  contain  about  nine  rolls,  the  top  and 
bottom  being  of  chilled  iron,  but  the  alternating 
intermediate  rolls  are  made  of  hard  paper.  An 
arrangement  of  compound  levers  admits  of  the  ap- 
plication of  several  tons  pressure.  The  paper  is 
either  run  through  a  dampener  and  sprayed  with 
water  before  calendering,  or  else  passes  over  steam- 
ing boxes  which  are  attached  to  the  calenders.  In 
this  moistened  condition,  the  paper  can  be  rolled 
flatter  and  smoother.  Quite  naturally  the  bulk  of 
such  paper  is  less  than  machine  finish  paper  of  equal 
weight  by  about  10  percent.  The  "supered"  rolls 
are  sheeted  or  packed  in  rolls  like  the  book  paper. 

Bonds,  Ledgers,  Writings,  Covers 

A  considerable  variety  of  finishes  are  given  to 
Bond  papers,  the  staple  finish  being  regular,  linen, 
and  ripple.  These  are  obtained  on  a  Plater  machine 
which  consists  of  two  heavy  rolls.  The  paper  is 
made  up  into  "books,"  being  interleaved  with  zinc 
plates,  for  a  smooth  finish,  and  rolled  back  and  forth 
between  the  rolls.  If  a  linen  finish  is  required, 
sheets  of  linen  are  alternated  with  the  paper  and 
with  a  number  of  zinc  sheets  so  that  the  squeezing 
of  the  plater  impresses  the  weave  of  the  cloth  into 
the  paper.  Any  suitable  substance  may  be  substi- 
tuted for  the  linen  sheets  to  impart  other  surfaces. 
Fancy  Cover  Papers  and  Pasted  Bristols  are  sur- 
faced in  the  same  manner.  Ledger  papers  are 
plated  with  zincs.  The  cheaper  grades  of  Writings 
are  finished  in  sheet  calenders  and  in  the  web. 


ESSENTIAL  FACTS  ABOUT  PAPER  29 

Bristol  Boards,  Blanks ',  Water  Finish  Wrapping 

Mill  bristol  blanks  and  water  finished  wrapping 
papers  receive  their  high  surface  on  the  calender 
stacks  of  the  paper  machine  to  which  so-called 
"water  doctors"  are  attached,  which  keep  a  number 
of  the  rolls  lightly  bathed  so  as  to  moisten  the  web 
before  calendering,  thus  leading  to  a  high  finish. 

Deckle  Edged  Papers,  Specialties 

In  the  ancient  hand-made  papers  the  four  edges 
of  each  sheet  had  a  feathered  edge  caused  by  leakage 
of  the  stuff  under  the  deckle  frame  of  the  hand 
mold.  Similarly,  machine-made  papers  have  feath- 
ered edges  on  each  side  of  the  web  next  to  the 
rubber  deckle  straps.  A  similar  effect  running 
with  the  grain  of  the  paper  can  be  had  by  squirting 
a  small  stream  of  water  at  the  desired  points,  but 
in  making  paper  by  machine  in  a  continuous  web, 
it  is  not  practical  to  get  a  deckle  edge  crosswise. 
Thus  one  is  enabled  to  tell  machine-made  from 
hand-made  paper,  as  it  has  two  smooth  edges  where 
it  is  cut  off  from  the  roll. 

Pasted  Papers,  Bristols,  Cover. 

Wedding  bristols,  and  double-thick  Cover  paper 
are  made  by  combining  one  or  more  rolls  over  a 
pasting  machine,  and  finishing  as  required  in  a 
plater.  A  Pasted  Bristol  can  be  identified  by  burn- 
ing, as  the  glue  will  melt  and  the  different  sheets, 
or  plies  of  which  it  is  composed,  sepajrate. 


30  ESSENTIAL  FACTS  ABOUT  PAPER 

Coated  Papers,,  Box  Specialty 

Coating  is  a  conversion  process,  many  coating 
mills  buying  their  stock  in  rolls  from  different 
sources,  particularly  if  their  product  is  much  diver- 
sified. A  mixture  is  made  usually  consisting  of 
China  Clay,  with  casein  as  an  adhesive  and,  suitably 
colored,  this  is  brushed  onto  the  web  of  paper  by 
means  of  a  special  machine.  As  the  paper  emerges 
with  its  fresh  coating,  it  is  automatically  caught  up 
by  sticks  in  a  conveyor  rack,  which  are  so  spaced  as 
to  carry  it  hanging  in  festoons  through  a  long  hot 
room  to  winders  where  it  rolls  up.  Many  special- 
ties with  metallic  coating  are  similarly  prepared. 
These  rolls  are  finished  as  desired.  Book  Coated  is 
run  through  super-calenders,  Glazed  Paper  through 
a  special  friction  calender  which  imparts  the  charac- 
teristic high  polish,  and  "Flint"  papers  through  a 
machine  where  it  is  automatically  polished  by  a 
smooth  flint  stone,  which  gives  the  highest  possible 
glaze.  Another  method  is  called  brushing ;  the  web 
in  this,  is  subjected  to  a  polishing  by  a  stiff  rotary 
brush.  These  latter  papers  are  used  principally  by 
the  box  trade  and  for  wrappers. 

Wrapping  Papers,  Tag,  Manila,  Kraft, 
Glassine,  Parchment 

The  principal  factor  in  wrapping  papers  is  maxi- 
mum strength  at  minimum  cost  except  in  the  spe- 
cialty field. 

Manila  wrapping  varies  in  grade,  the  cheaper 
having  the  larger  percentage  of  ground  wood.  The 
strength  is  supplied  by  unbleached  sulphite  pulp. 


ESSENTIAL  FACTS  ABOUT  PAPER  31 

Kraft  Paper  is  the  best  grade  of  Wrapping,  it  is 
composed  of  sulphate  pulp  and  no  ground  wood. 
Hence  although  more  costly  by  the  pound,  its 
greater  strength  allows  of  using  a  lighter  weight, 
so  that  on  a  basis  of  suitable  strength  and  yardage 
cost,  it  has  gained  an  important  place  in  the  wrap- 
ping field  and  makes  a  more  sightly  paper  than  the 
so-called  Manila. 

Tag  stock  varies  in  quality  from  a  cheap  so-called 
Manila  to  a  stout  Jute  Manila  suitable  for  rough 
usage. 

Glassine  Paper  is  comprised  of  straight  sulphite 
stock  either  bleached,  unbleached  or  a  mixture  of 
the  two  according  to  the  appearance  and  transpar- 
ency required.  Its  transparent  and  grease-proof 
qualities  are  entirely  effected  by  special  beating  and 
super-calendering  without  the  use  of  acids.  It 
makes  a  particularly  hygienic  and  attractive  paper 
for  food  products,  or  for  packages  where  protection 
and  transparency  are  both  necessary.  Fancy  pat- 
terns are  also  embossed  in  glassine,  which  renders  it 
peculiarly  attractive  for  dainty  packages  and  spe- 
cial purposes. 

Vegetable  parchment  is  prepared  by  giving  paper 
a  sulphuric  acid  bath.  The  paper  passes  from  the 
roll  through  the  acid  and  between  squeeze  rolls 
which  remove  the  excess  liquor,  then  it  is  washed  off 
with  fresh  water,  neutralized  of  its  acid  and  dried. 
The  process  not  only  strengthens  the  paper,  but 
renders  it  grease  proof. 


CHAPTER  V 

THE  PHYSICS  OF  PAPER 

Effects  of  Moisture 

No  characteristic  of  paper  is  more  important  to 
appreciate  than  its  sensitiveness  to  atmospheric  con- 
ditions. Paper  might  be  called  "hygrometrical," 
if  there  is  such  a  word,  as  it  is  susceptible  to  every 
change  in  the  atmosphere.  A  certain  percentage 
of  moisture  is  normal  to  paper,  varying  with  the 
relative  humidity  of  the  air.  In  absorbing  mois- 
ture, cellulose  fibres  expand  in  diameter  and  in  dry- 
ing shrink,  as  has  been  mentioned  in  the  description 
of  paper  making.  It  was  also  shown  that  a  majority 
of  fibres  in  machine-made  papers  lie  parallel  to  the 
direction  in  which  they  are  made.  Hence  as  paper 
absorbs  moisture  it  expands  across  the  grain  of  the 
sheet,  so  that  a  distinctly  pronounced  stretch  may 
be  noted  after  a  change  from  dry  to  damp  weather. 

This  is  the  cause  of  poor  "register"  in  printing. 
It  also  accounts  for  wavy  edges,  for  as  paper  lies  in 
a  pile  the  interior  is  not  exposed  and  remains  con- 
stant, whereas  expansion  occurs  along  the  edges, 
resulting  in  a  cockled  effect,  often  troublesome  to 
printers  if  it  occurs  along  the  gripper  edge. 

The  Grain 

On  this  account  it  is  usually  preferable  to  have 
the  grain  run  the  long  way  of  a  sheet,  but  this  rule 
has  its  exceptions,  and  frequently  it  is  of  slight  im- 
portance. Whenever  close  register  is  required, 
however,  the  importance  of  grain  direction  is 
greatest. 

32 


ESSENTIAL  FACTS  ABOUT  PAPER  83 

In  the  binding  of  books,  the  moisture  of  the  glue 
will  cause  a  permanent  cockle  if  the  paper  is  "cross 
grained."  This  can  be  avoided  by  having  the  grain 
run  parallel  to  the  shelf  back. 

The  fact  that  it  is  impossible  to  make  paper 
exactly  acclimated  to  various  atmospheres,  is  the 
reason  paper  should  be  racked  by  the  printer  in  an- 
ticipation of  color  printing,  and  thus  given  a  chance 
to  become  seasoned. 

Aside  from  the  importance  of  grain  direction  in 
reference  to  atmospheric  conditions,  the  folding  re- 
quirements must  be  considered.  Paper  folds  well 
with  the  grain,  but  thick  sheets  are  likely  to  crack 
when  folded  across  the  grain.  A  book  bound  cross- 
grained  is  decidedly  less  flexible  and  opens  less 
easily.  English  binders  evince  a  preference  for  a 
cross-grained  binding  because  the  sewing  passes 
around  the  fibres,  and  signatures  are  less  likely  to 
pull  loose.  It  seems  to  us  preferable  to  select  stock 
sufficiently  strong  to  withstand  reasonable  wear  and 
tear,  and  to  have  the  flexibility  and  freedom  from 
cockling  which  can  be  insured  by  the  grain  parallel 
with  the  back. 

Some  catalogs  of  large  page  size  might  be  im- 
proved on  the  other  hand,  by  the  greater  rigidity 
which  results  from  having  the  grain  at  right  angles 
to  the  binding. 

In  order  to  detect  the  direction  of  grain  in  paper 
two  simple  tests  may  be  suggested.  Cut  out  a 
small  square  and  moisten  one  side.  The  expansion 
of  the  fibres  will  cause  it  to  curl  dry  side  in,  and 
the  axis  of  the  cylinder  thus  formed  will  be  with 
the  grain. 


34  ESSENTIAL  FACTS  ABOUT  PAPER 

Cut  two  narrow  strips  of  paper,  about  four  inches 
long  either  way  of  the  sheet,  place  them  so  they 
coincide  and  hold  by  one  end  in  a  horizontal  position. 
If  the  grain  happens  to  be  in  the  long  dimension  of 
the  under  strip,  it  will  keep  in  contact  with  the 
upper  because  of  its  greater  stiffness.  Reversing 
the  strips,  the  under  one  being  now  cross-grained, 
will  sag  away  at  the  free  ends  on  account  of  its 
greater  flexibility.  In  cutting  cards,  it  is  important 
to  see  that  the  grain  is  the  long  way  if  a  snappy 
card  is  preferred. 

Static  Electricity  in  Paper 

The  amount  of  moisture  in  the  air  has  a  marked 
effect  on  the  behavior  of  paper  in  relation  to  static 
electricity,  with  which  it  often  becomes  charged  by 
friction.  This  trouble  is  at  its  height  in  cold,  dry 
weather,  as  there  is  then  a  minimum  of  moisture  in 
the  air,  which  under  such  conditions  lacks  in  con- 
ductivity. The  most  simple  expedient  to  avoid  this 
trouble  is  to  keep  the  press  room  warm,  and  to 
humidify  the  air,  which  may  be  done  by  opening  a 
pet  cock  in  a  steam  radiator.  There  are  two  well 
known  devices  for  neutralizing  electricty  on  print- 
ing presses.  One  consists  of  a  gas  pipe  with  fre- 
quent small  jets  of  flame  close  to  which  the  sheets 
must  pass  in  transit  to  the  delivery  board.  The  heat 
skims  over  the  ink,  minimizing  the  likelihood  of 
offsetting  and  the  flame  provides  a  conductor  for 
electrical  charges.  The  other  apparatus  is  called 
an  electrical  neutralizer.  An  alternating  current  is 
discharged  from  points  onto  the  sheets  of  paper  as 


ESSENTIAL  FACTS  ABOUT  PAPER  35 

they  pass,  and  as  static  charges  are  both  positive 
and  negative,  they  naturally  select  the  current  of 
the  opposite  polarity  from  the  discharge  of  the  neu- 
tralizer,  and  are  destroyed.  Consequently,  the 
sheets  reach  the  delivery  board  in  a  neutral  con- 
dition. 


CHAPTER  VI 

QUALITY  AND  TESTING 

The  basis  of  quality  in  paper  can  scarcely  be  de- 
fined other  than  to  say  it  is  the  maximum  suitability 
for  its  intended  use.  As  between  several  suitable 
papers  there  is  to  be  considered  the  appearance, 
strength,  and  composition. 

Appearance 

To  the  eye  of  a  beginner  the  finer  distinctions  in 
appearance  are  elusive,  and  only  after  continued 
observation  do  they  become  apparent.  Among  the 
more  noticeable .  are  even  sidedness,  cleanliness, 
brightness  of  color,  and  uniformity  of  surface.  A 
constant  comparison  of  samples  is  the  only  way  to 
acquire  discrimination. 

Strength 

Strength  may  be  assessed  by  the  practiced  hand 
by  tearing  in  both  directions  of  the  grain.  Crum- 
pling a  paper  repeatedly  and  observing  how  easily 
and  numerously  holes  occur  is  also  a  very  practical 
test. 

Folding  backwards  and  forwards  is  another  good 
method  in  the  absence  of  any  precise  testing  ma- 
chine. Any  well  equipped  laboratory  is  supplied 
with  machines  which  accurately  record  the  bursting 
strength,  the  tensile  strength,  and  the  number  of 
folds  a  paper  will  withstand  at  a  given  tension. 

36 


ESSENTIAL  FACTS  ABOUT  PAPER  37 

Composition 

Tests  for  determining  the  kind  of  fibre  and  other 
constituents  can  be  but  roughly  performed  outside 
of  a  chemical  laboratory,  or  by  other  than  trained 
analysts. 

It  is  frequently  desirable  to  detect  the  presence 
of  ground  wood  and  this  may  be  ascertained  by  a 
drop  of  phloroglucine,  which  leaves  a  red  spot  on 
paper  containing  ground  wood,  the  intensity  of  the 
shade  being  in  proportion  to  the  quantity  present. 

Strong  nitric  acid  will  show  a  brown  reaction  in 
the  presence  of  ground  wood,  but  this  test  is  less 
delicate. 

A  rough  idea  of  the  mineral  content  may  be  had 
by  burning,  as  the  quantity  of  ash  is  proportionate 
to  the  amount  of  the  non-combustible  filler. 

Experience  is  the  best  guide  in  these  matters,  and 
above  all  only  such  tests  may  sensibly  be  applied 
as  are  significant  for  the  purposes  to  which  the 
paper  is  intended.  A  bursting  test,  for  example, 
is  decidedly  appropriate  to  container  board  which 
must  withstand  thrusts  and  contusions,  but  is  far 
less  significant  of  the  qualities  of  a  printing  paper. 

Dependability 

In  our  Purchasing  department  these  points  are 
always  carefully  taken  into  consideration  in  the 
selection  of  our  stock  goods,  and  further  than  this 
we  know  from  experience  what  mills  may  be  de- 
pended upon  to  maintain  uniformity  of  production 
and  reliability  of  standards. 

The  papers  we  sell  under  the  mill  brands  are  well 


38  ESSENTIAL  FACTS  ABOUT  PAPER 

known  for  their  high  standards  and  reliability.  We 
are  no  less  careful  in  the  selection  of  manufacturers 
for  such  brands  as  are  made  especially  for  us,  and 
sold  under  our  private  trade  names. 

It  is  our  business  to  be  discriminating  and  careful 
in  the  selection  of  all  the  papers  we  regularly  stock, 
as  we  fully  appreciate  that  "re-orders"  are  the  final 
test  of  all  successful  papers  and  a  paper  that  cannot 
hold  its  own  in  the  estimation  of  our  customers  will 
not  long  survive. 

The  many  years  that  we  have  been  in  the  paper 
business  are  the  best  proof  of  the  dependability  of 
our  stock  which  represents  only  the  survival  of  the 
fittest,  which  is  after  all  the  ultimate  test  of  quality 
in  paper. 


UHIV.  OF 


CALIF.  LIBRAE* ,  LOS  ABGELE3 


A     000  089  442     8 


University  c 

Southern 

Library 


